To introduce the new and robust technology of MHC class I tetramers for the quantification of immune responses in melanoma patients involved in a multi-institutional phase III clinical trial. Recent evidence suggests that circulating CD8+ T cells in melanoma patients may be present in relatively large numbers but may be impotent. Therefore, we will assess the functional potential of melanoma-specific CD8+ T cells by examining their response to peptide stimulation using a combination of MHC tetramer staining, together with analysis of intracellular cytokine production.